Control mechanism for use in electric controllers



Sept. 10, 1929. c. T. NEAL 2 v CONTROL MECHANISM FOR USE IN ELECTRIC CONTRQLLERS Original Filed Aug. 8, 1921 i QM I I INVENTOR *2: jfl

- J BY ATTORNEYS.-

' Patented Sept. 10, 1929.

A UNITED STATES PATENT OFFICE.

CHESTER '1. NEAL, F SPRINGFIELD, MASSACHUSETTS, AssIGNoE, BY MESNE, AS- sIeavME-N'rs, ro THE STUEBING-COWAN coMPANY, 0F CINCINNATI, OHIO, a com PORA'IION OF OHIO.

CONTROL MECHANISM FOR USE IN ELECTRIC CONTROLLERS.

Application filed August 8, 1921, Serial No. 490,783. Renewed February 19, 1929.

The present invention relates to electric controllers and more particularly to safety control mechanism for use in connection therewith to render the controller inefi'ective under certain conditions.

Although capable of a more general application, the invention is especially adapted for use in connection with controllers employed in motor driven vehicles of the type known commercially as industrial trucks or tractors.

To adequately control and safeguard the operation of industrial trucks it is customary to equip them with a manually operable controller and with automatic safety control devices comprising a cut-out switch in the controller circuit, a foot treadle or the like adapted to be normally held depressed by the operator, and connections between the treadle and the switch whereby the latter will be opened to break the controller circuit when the tre-adle is released. To prevent the possibility of the motor being started at high speed and thereby imposing an unnecessary strain upon the motor and batteries,

provision is sometimes made for preventing the closing of the cut-out switch when the treadle is again depressed unless the controller has been previously returned to neutral or off position.

The object of the present invention is to provide certain improvements in the construction and mode of operation of safety control mechanism of the above described general character.

To this end, theinvention consists in the features of construction and combinations and arrangements of parts hereinafter described and particularly pointed out in the appended claims, the advantages of which will be apparent to those skilled in the art.

The invention will be readily understood from the following description of the pre- 'l'errcd embodiment thereof illustrated in the accompanying drawings, in which Fig. 1 is a View, in front elevation, of an electric controller provided with improved safety control mechanism constructed in accordance withthe present invention; and

the line 2-2 of Fig. 1;

Referring to the drawings, an electric controller is indicated at 5, the controller comprising a controller drum 6 having the usual contact plates 7 and cooperating Still". tionary contact fingers 8, all of which are enclosed within a cylindrical casing 9;

The controller drum 6' is secured to a shaft 10 which is journaled in bearings at theopposite ends of the controller casing. The controller is adapted to be manually operated by means of the usual handle 12 thatis rigidly secured to the drum shaft 10 at one end thereof which projects outside of the controller casing. Suitable conductors '(not shown) connect the contactplates 7 and contact fingers 8'with a motor 14 and battery (not shown),--and as the controller drum is turned by the handle 12 the necessary connections are made to effect the gradual acceleration of the motor in either forward or reverse directions, according to the direction of rotation of the drum.

In the controller circuit is a cut-out switch constituting a portion of the'safety control mechanism hereinbefore referred to and which is particularly designed for use on so-called industrial trucks or the like. The cut-out switch comprises cooperating, separable terminals or cont-act members 15..

- and 16, the terminal 15 being in the'form of an arcuate plate secured to the periphery of a disk 17 carried at one end of a sleeve 18' that is rotatably mounted upon the controller shaft 10, within the cont-roller casinga.

9, while the terminal 16 is in the form of a finger mounted upon the interior of the controller casing.

The switch sleeve 18 is acted upon by means which constantly tend to maintain the cut-out switch in open condition or to restore the switch to open condition if it has been closed. As best shown in Fig. 2 this means comprises a pair of fingersQOfthe casing. The pivoted fingers 20 extend upwardly upon opposite sides of the switch lower ends of which are pivotally mounted .upon' a stud 21 projectingfrom a bracket 22 formed on the interior ofthe controller sleeve, and are yieldingly held against the sleeve by means of springs 23 which press inwardly against the upper ends of the fingers. To this end, the springs 23 are coiled around the opposite end portions of a rod 2d that extends loosely through apertures in the upper ends of the fingers 20. The springs 23 are severally interposed between the respective fingers 23 and nuts 25 which are threaded upon the ends of the rod 24c and may be turned to adjust the tension of the springs. The exterior of the portion of the switch sleeve 18 between the fingers 20 is elliptically shaped to provide cam projections 26 normally positioned relatively to said fingers as represented in Fig.

\ 2. With this construction, where the switch sleeve is turned in either direction, the pivoted fingers 20. will be spreadapart and the springs 23 put'under compression so that the force of the springs will tend to return the switch sleeve and disk to their normal radial positions in which the cut-out switch is open.

To enable the cut-out switch to be automatically closed when the handle 12 is turned toshift the controller and start the motor, the switch sleeve 18 is adapted to be connected to turn with the controller shaft 10 by means of a slidable clutch collar 30 said shaft rat the opposite end of the controller casing from the handle 12. As shown, theclutch collar 30 is provided with a clutch tooth 31 for engagement with a notch 32 in the adjacent end face of the switch sleeve 18. The notched portion of the switch sleeve thus constitutes a clutch member complemental to the'clutch member or collar 30. The clutch collar, 30 is constantly urged to- I ward the switch sleeve. by means of a spring 33 which is coiled about the controller shaft, one end of the spring bearing against the flanged outer endof the clutch collar 30 while the opposite end of the spring bears against a collar 34 held on the shaft by the head 35 of a bolt which is threaded axially into theend of the shaft. i

In order that the operation of clutching the switch sleeve '16 to the controller shaft may be controlled by the operator, the clutch collar 30 is connected with a foot treadle 36 and provision is made whereby so long asthe foot treadle is allowed'to remain in its normal or elevated position, the clutch collar 30 will be held disengaged from the switch sleeve 16, but. when the treadle is depressed,

the spring 33 will be operated to slide the clutchcollar toward the switch sleeve. To

this end the treadle 36 is connected byalink 37 with one end ofan arm 38,, the central portion of which is keyed to a rock-shaft 39 that 10 with the lower arm of a bell-crank lever 41 that is fulcrumed in a bracket 42 secured to the controller casing 9. The upper arm of the bell-crank lever 41 is forked to straddle the clutch collar 30 and the forked ends of said'arm carry inwardly projecting studs 43 the sides of which engage an annular flange 44 on the clutch collar 30. The parts just described are held in the positions in which they appear in Fig. 1 by means of a spring 45 which is secured at one end to the arm 38 adjacent the rod and at the opposite end to a stationary part of the truck frame. The spring is stronger than the spring 44 and normally holds the latter compressed, maintaining the clutch collar 30 disengaged from the switch sleeve 18 and the foot treadle 36 in its elevated position.

lVith this construction it will be seen that while the treadle is allowed to remain elevated, the switch sleeve will be unclutched from the controller shaft and the switch will therefore be maintained in open condition by the action of the springs 23. Therefore, al

sition, the bell-crank lever 41 will be rocked, through its connections with the treadle, in a direction to enable the spring 33 to slide the clutch collar 30 into cooperative engagement with the switch sleeve 18. Thereafter, so long as the treadle remains depressed, the turning of the controller handle will effect the turning of the switch disk 17 and the construction and arrangement of the parts is such thatthe switch will be closed when the controller drum is turned to an operative or 011" position. Therefore, when the controller reaches the on position the controller circuit will be completed and the motor will be started.

j the motor stopped.

If, however, the controller is left in on position the operator cannot then start the motor by depressing the treadle for although this action tends, through the connections between the treadle and the clutch collar 30 to reengage the clutch collar and switch sleeve, such engagement cannot be effected while the controller remains in on position, inasmuch as the clutch tooth 31 will not register with the notch 32 in the switch sleeve except when the controller is in ofi position. The

ing the controller handle from its 011' po- 5 which is splined to a projecting portion of brake drum to prevent rotation of depression of the treadle therefore will mercly cause the clutch collar to be held with the tooth 31 in pressing contact with the end face of the switch sleeve but not in engagement with the notch 32. If, while the treadle remains depressed, the operator returns the controller handle to off position, the clutch tooth 31 will then snap into engagement with the notch 32 and the operator thereafter may, by turning the controller handle, both close the cut-out switch and move the controller drum to an on position. The controller circuit will then be completed and the motor started.

In order that the anotor and the truck shall be stopped quickly whenever the operator releases the treadle and thus unclutches the switch sleeve 18 from the controller shaft so that the cut-out switchis opened and the controller circuit broken, a braking device is provided for checking the momentum of the motor armature at such times. It will be understood that the motor armature shaft is connected in the usual waywith the driving wheels of the truck so that stopping of the motor armature shaft will also stop the wheels of the truck. To this end,

stud 50. The brake shoes 49 are provided at the opposite side of the brake drum from the pivot stud 50, with substantially parallel, outwardly extending arms 51. Loosely extending through the free ends of the brake shoe arms 51 is a rod 52 which carries adjustable nuts 53 and also a spring 54 which is coiled around the rod 52 between one of the arms 51 and one of the nuts 53, the other nut being held in engagement with the other arm 51 by the force of the said spring. The arrangement is such that the spring 54 tends to force the brake shoes against the the latter. The brake shoes are adapted to be held out of engagement with the brake drum by means of a spreader cam 55 which is rigidly secured to the rock shaft 39 and is disposed between the arms 51 of the brake shoes. The spreader cam 55 is so arranged that when turned it will spread the brake shoes apart against the force of the spring 54 and release the brake drum for rotation.

It will be noted that the brake for the motor shaft is controlled through the operation of the treadle 36, which treadle also is adapted to control the operation of the cut-out switch of the controller. When the treadle 36 is fully released and in its uppermost position, the brake mechanism operates to stop the motor shaft, and the vehicle and the cut-out switch is operated to shut off current to the motor.

operation of such vehicles to be able to check the speed of the vehicle slightly to avoid a momentary obstacle without shutting off the power completely and for this reason it is desirable to be able to apply the brake while still keeping the power on.

In the present apparatus provision is made for causing the brake shoes 49 to grip the brake drum 48 some time before the clutch tooth 31 is disengaged from the notch 82 in the switch sleeve 18. To this end the connections between the lever 41 and the treadle 36 are so designed that the stud 43 travels through an arc somewhat greater in length than the distance travelled by the clutch collar 30 and consequently when the treadle 36 is depressed to its final position the stud 43 will be separated by a short distance from the flange 44 of the collar 30. Thus upon the release of the treadle the stud 43 will move idly through the space separating it from the flange 44 and during this idle movement of said stud the spreader cam 54 will permit the brake shoes 49 to grip the brake drum 48 so as to be im1nediately effective to prevent further rotation in either direction of themotor shaft 47 after the clutch collar 30 has been shifted and the motor has been stopped by the return of the cut-out switch 16 to its open condition.

With this construction it is obvious that when the truck orvehicle is to be started for the purpose of ascending an incline from a position of rest thereon, the treadle 36 may be operated so that the clutch tooth 31 will enter the notch 32 so as to clutch the switch sleeve 18 to the controller shat be fore the spreader cam 54 becomes operative to release the brake shoes 49. Consequently by turning the controller 12 to start the motor before the treadle has been fully depressed to its final position, the operator will insure against retrograde movement of the vehicle before it'starts to move forwardly up the incline.

The invention has been disclosed herein, for illustrative purposes, in an embodiment at present preferred but the scope of the invention is defined by the appended claims rather than by the foregoing description.

What l claim is Q l. The combination with a controller drum and its shaft, of a longitudinally immovable sleeve rotatably mounted on the controller lOO shaft and having a notch in one end thereof, a cut-out switch in the controller circuit having one of its contacts carried by said sleeve, a clutch member splined on theocontroller shaft for sliding movement toward and away from said sleeve and having a clutch tooth adapted to enter said notch when the latter is in registry therewith, the parts being constructed and arranged so that the notch will register with the tooth only when the switch is open, a spring constantly urging the clutch member toward the sleeve, a lever normally in engagement with said clutch member, a spring connected with said lever to move the clutch member away from the sleeve, said spring normally acting, against the force of the first spring tending to hold the clutch member disengaged from the said sleeve, a foot treadle connected with said lever and adapted to be depressed to a predetermined position to move said lever out of contact with said clutch member if the movement of the latter is arrested before the treadle has reached its predetermined position by reason said notch being out of registry with said tooth.

2. The combination with a rotatable con troller drum fora circuit, a cut-out switch for said circuit comprising a separately rotatable clutch member carrying a terminal of said switch, a coacting driving clutch member carried with said controller drum, a spring tending to hold said clutch members toward one another for engagement, a manually controlled lever having a move ment in one direction to separate said clutch members and a movement in the opposite direction irrespective of any movement of said clutch members.

8. The combination with a rotatable controller drum for a circuit, a cut-out switch for said circuit comprising a separately rotatable clutch member carrying a terminal of said switch, tension means normally tending to maintain said clutch member with its terminal in open position, a coacting driving clutch member carried with said controller drum for rotating said first clutch member to bring its terminal to closed position, a spring tending to hold said clutch members toward one another for engagement, a manually controlled lever having a movement in one direction'toseparate said clutch members and a movement in the opposite direction irrespective of any movement of said clutch members.

i. The combination with a rotatable con troller drum for a circuit, a cut-out switch for said circuit comprising a separately rotatable clutch member carrying a terminal of said switch, a coacting driving clutch member carried with said controller drum,

a spring tending to hold said clutch members toward one another for engagement, a lever having a movement in one direction to separate said clutch members and a movement in the opposite direction irrespective of any movement of said clutch members, a second spring strong enough to overcome said first spring and acting upon said lever in the first named direction, and a foot trcadle adapted when depressed to act upon said lever in the last named direction.

5. The combination with a controller drum, of a driving clutch member rotatable with the drum, a driven clutch member, separable terminals in the controller circuit one of which is carried by the driven clutch member, a spring tending to move the clutch members toward one another, a second stronger spring normally acting against the force of the first spring to maintain the clutch members separated, and a foot treadle operating when depressed to overcome the force of said second spring and allow said first spring to effect engagement of the clutch members whereby the controller cir-' cuit may be closed by the rotation of the controller drum.

6. The combination with a controller drum and its shaft, of a driven clutch member rotatably mounted on said shaft, a cooperating driving clutch member rotatable with the controller shaft and slidable thereon toward and from the driven clutch member, separable terminals in the controller circuit one of which is carried by said driven clutch member, a spring tending to move the driving clutch member toward the driven clutch member, a lever movable in one direction for shifting the driving clutch member out of engagement with the driven clutch member, a second stronger spring for actuating the lever in said direction against the force of said first spring and a foottreadle operating when depressed to overcome the force of said second spring and allow said first spring to ebifect the engagement of said clutch memers.

7. The combination with a controller drum and its shaft, of separable terminals in the controller circuit, a collar splined on the controller shaft for movement longitudinally thereof having a clutch tooth formed thereon, a longitudinally immovable sleeve mounted on said shaft carrying one of said terminals and having a notch in one end face adapted to be positioned to receive said clutch tooth only when the terminals are separated to break the controller circuit, a spring constantly urging said collar toward said sleeve, a lever movable in one direction for slidingsaid collar away from said sleeve to disengage said tooth and notch the lever being free to move irrespective of the collar in the opposite direction, and a foot treadle connected with said lever and acting when depressed to move said lever in the last named direction and a second spring stronger than said first spring tending to normally hold said foot treadle elevated and said collar away from said sleeve.

8. In combination, a controller drum, a cut-out switch, a connection between the controller drum and the cut-out switch for operating the cut-out switch simultaneously with the controller drum comprising a clutch, yieldable means tending to move the cut-out switch to oil position, yieldable means tending to disconnect said clutch, manually operative means for controlling said clutch including a lost motion connection said clutch and manually operable means being so constructed and arranged that the clutch can beconnected only when the controller drum is in the oil position.

9. In apparatus as claimed in the preceding claim, the arrangement of a brake and connection between the manual clutch operating means and the brake for releasing the brake, said means being operable to release the brake after the clutch is connected.

10. In apparatus of the character described, in combination, a rotatable controller drum, arotatable cut-out switch, a connection between the controller drum and the cut-out switch for rotating the cut-out switch simultaneously with the drum comprising a clutch, yieldable means tending to rotate the cut-out switch to oil position, yieldable means tending to disconnect the clutch, manually operative means for engaging said clutch comprising a lost motion connection, and a brake, said manually operable means being constructed and arranged to release said brake after the clutch is engaged.

In testimony whereof I have aflixed my signature.

CHESTER T. NEAL. 

